Oops: Lufthansa Jet Diverts Twice In A Row Due To Pressurization Issues

Most of us would like to believe that if a plane diverts due to a mechanical issue, that it’s thoroughly inspected before reentering service, so that the same thing doesn’t happen again. Well, here’s a situation where a plane diverted on two flights in a row, for very similar reasons, as reported by The Aviation Herald.

Lufthansa CityLine CRJ-900 returns to Frankfurt twice

This incident involves a 13-year-old Lufthansa CityLine CRJ-900 with the registration code D-ACNX, which is typically stationed in Frankfurt (FRA).

On April 21, 2025, the jet was supposed to perform the 394-mile flight LH1390 to Poznan (POZ). At 9:40PM the aircraft departed runway 18, but the crew stopped the climb at 22,000 feet, and decided to return to Frankfurt.

The reason? The crew reported that there were pressurization problems with one of the doors, and there was a loud noise in the cockpit. The aircraft landed back in Frankfurt on runway 25L around 25 minutes after it first departed, at 10:05PM.

The aircraft then spent a bit over eight hours on the ground (it’s not clear what kind of work was performed on the plane). Then on April 22, 2025, the jet was supposed to perform the 254-mile flight LH1220 to Salzburg (SZG). At 6:51AM the aircraft departed runway 18, but the crew stopped the climb at 25,000 feet, and decided to return to Frankfurt.

The reason? The crew reported that there were pressurization problems… again! The aircraft landed back in Frankfurt on runway 25C around 30 minutes after it first departed, at 7:21AM.

The aircraft was then properly taken out of service

Following the second return to Frankfurt, the aircraft spent roughly 31 hours on the ground, clearly for mechanics to take a closer look at the aircraft. At that point, on the afternoon of April 23, the aircraft performed a 45-minutes test flight, presumably to ensure that the same issue didn’t arise yet again.

The aircraft then once again reentered passenger service on the night of April 23, operating a flight to Poznan, 48 hours after the whole ordeal first started.

One would certainly assume that the aircraft was inspected when it spent the night on the ground between the first and second diversion. How the issue seemingly wasn’t discovered is beyond my area of expertise.

This isn’t the first time that we’ve seen something like this. For example, several weeks ago I wrote about an American 787 that diverted four times in 25 days, even though the plane spent 19 of those 25 days in maintenance. While computer systems are designed to help with troubleshooting what might be wrong, obviously that doesn’t always work as intended.

Bottom line

A Lufthansa CityLine CRJ-900 diverted on two flights in a row due to pressurization issues. It’s not often you see planes divert for the same reason on two flights in a row. After the second diversion, maintenance took a closer look, the plane was grounded for a day, and it then performed a test flight before reentering service.

What do you make of this Lufthansa CRJ-900 double diversion?